In utero repair of diaphragmatic hernia.

This report describes the first in utero repair of diaphragmatic hernia in Australia. The patient was a 32 year old woman with major infertility problems who was diagnosed at 15 weeks gestation as having an infant with diaphragmatic hernia. After extensive consideration and counselling the parents requested in utero repair. This was performed at 28 weeks gestation and was technically successful, but the infant was found to be dead after uterine closure. The mother has subsequently been delivered of normal twins at term by Caesarean section. In utero repair of diaphragmatic hernia requires a high degree of team work, is technically demanding and has major ethical implications. It should be restricted to nationally designated units.

Effect on the fetus of infusing a commercial amino acid preparation into a pregnant sheep.

The common clinical practice of intravenous feeding of the pregnant woman poses the question of the effect on the fetus of such infusions. We have used the sheep as a model to study the change in fetal amino acid levels after a maternal infusion of Synthamin 13. The maternal plasma aminogram largely reflects the amino acid pattern in the infusate. However, in the fetal circulation only the branched chain amino acids (leucine, isoleucine and valine), phenylalanine and alanine rose significantly after infusion. Only leucine and isoleucine were observed to spill into the fetal urine. The results suggest that the ovine placenta selectively modifies the amino acid profile presented to the fetus when the maternal plasma aminogram is distorted. However, the fetus is not totally protected from changes in phenylalanine, which in high concentrations, is detrimental to normal development.

Changes in plasma amino acids in the developing chick.

We have sampled arterial blood from chicken embryos during development and measured the changes in plasma amino acids from mid-gestation to hatching. During gestation, several amino acids rise to a peak concentration at 16 days and fall prior to hatching. After hatching, most amino acids fall, although the plasma concentrations of aspartate, glutamate and taurine rise significantly.

Increased arterial pressure variability after arterial baroreceptor denervation in fetal lambs.

Baroreceptor reflexes can be demonstrated during fetal life, but whether baroreceptors normally regulate fetal arterial pressure is unknown. This problem was addressed directly by measuring arterial pressure and analyzing its variation in eight unanesthetized fetal lambs throughout the last third of gestation, and comparing these data with similar measurements made in seven fetal lambs with denervated arterial baroreceptors. Measurements were made at 5-minute intervals over 24 hours in a total of thirty-three experiments. The coefficient of variation of mean arterial pressure (standard deviation of mean arterial pressure/mean value of mean arterial pressure) expressed as a percentage was used as an index of blood pressure variability. Coefficients averaged 7.0% in intact lambs and 12.1% in barodenervated lambs (P less than 0.001), signifying considerably increased variability of mean arterial pressure after barodenervation. Mean arterial pressure averaged over 24 hours was not different between the two groups prior to 120 days (0.8) of gestation. Between 120 days and term, mean pressure was significantly greater in the denervated fetuses (65 cm H2O) than in the sham-operated controls (60 cm H2O, P less than 0.025). These data demonstrate that a baroreceptor-blood pressure reflex functions during late gestational development in lambs and signify an important role of arterial baroreceptors in regulating fetal arterial pressure. Failure to regulate arterial pressure in the barodenervated fetus could result in significant alterations in placental perfusion and exchange, and in the regional delivery of oxygen and substrates to developing organs in these animals.